1. Field of the Invention
This invention relates to an improvement in a touch roller device for a winding apparatus for winding up a web or the like which makes pressure contact with a wind roll wound on a winding shaft.
2. Description of Related Art
In winding a web, a winding shaft, on which the web is wound, is rotated by a motor or other drive means to impart a tension to the web, thereby winding it up as a wind roll. In that process, air is entrained between an outer circumferential surface of the wind roll and the web approaching onto the wind roll. In order to adjust the quantity of air entrapped, a roller called a touch roller is provided at a position of the surface of the wind roll where the web approaches and adjusts the pressure of its contact with the wind roll, so that an optimal wind roll is ultimately obtained.
Hitherto the touch roller has been controlled for optimal contact pressure in a manner that its position changes with an increase in diameter of the wind roll and its pressure of rotational movement changes as a contact pressure to the wind roll, but because of a significant error, it has been difficult to obtain an optical contact pressure.
With a view to obtaining an optical contact pressure, therefore, improvements over the conventional touch roller have been investigated, one of which has resulted in a touch roller device as shown in FIG. 3. The device is constructed so that a touch roller 3 is provided at the top end of a touch roller arm 2 to be rotatable with the turning movement of the arm 2 and the approaching direction of the web W to the touch roller 3 and the wrapping direction around the wind roll R making pressure contact with the touch roller 3 are kept in parallel, whereby a total tension loaded on the touch roller 3 acts on the center of it without affecting the direction of the wind roll (cf. JP UM Publication 63(1988)-23389 Y2).
More specifically, the aforesaid device is comprised of one touch roller, the approaching direction of the web to the touch roller being 180xc2x0 to the outgoing direction from the touch roller and the web embraces or wraps the touch roller by 180xc2x0, namely, its half circumference.
The web is wound, being stabilized in a manner that the web immediately before wrapping on the wind roll embraces the touch roller contacting with the wind roll at a suitable angle to the touch roller so as to prevent the web from widthwise laterally shifting. Here, since the touch roller is in pressure contact with the wind roll, air remains between the web lapping the touch roller and the surface of the touch roller and is wound within the web in the form of small wrinkles.
It is therefore essential not to entrain air between the touch roller surface and the web lapping the touch roller. Otherwise, it is preferable that the air, even if entrained, readily escapes and the web does not lap much of the surface of the touch roller.
Moreover, the approaching angle of the web to the touch roller varies in a wide variety of conditions of the web, e.g., characteristics, thickness, width, winding speed and so on, and is not always definite.
In order to tackle with the current situation above, the present invention is aimed at obstructing the entrainment of air by altering and adjusting the approaching angle of the web to the touch roller and, further, at simply substituting an optimal touch roller suitable for webs which vary in physical properties, thickness, width, winding speed, etc., thereby enhancing the quality of the wind roll and the work efficiency.
A first invention for attaining the aforesaid objects resides in a touch roller device for a web winding apparatus disposed at a position of the web approaching a wind roll being wound on a winding shaft, which device comprises a touch roller disposed in pressure contact with an outer circumferential surface of the wind roll; a guide roller disposed adjacent to and upstream of the touch roller; and touch roller arms spaced apart and provided with both the touch roller and guide roller therebetween, the touch roller and the guide roller being in such a positional relation that the approaching direction of the web to the guide roller and the wrapping direction of the web around the wind roll in pressure contact with the touch roller are generally parallel to each other, the position of the guide roller being controllable in the vertical direction so that the approaching angle of the web to the touch roller making pressure contact with the wind roll can be adjusted.
A second invention resides in a touch roller device for a web winder disposed at a position of the web approaching a wind roll under winding on a winding shaft, which device comprises a touch roller disposed in pressure contact with an outer circumferential surface of the wind roll; one or two guide roller disposed adjacent to and upstream of the touch roller; and touch roller arms spaced apart and provided with both the touch roller and guide roller, the touch roller and the guide roller being in such a positional relation that the approaching direction of the web to the guide roller and the wrapping direction of the web on the wind roll in pressure contact with the touch roller are generally parallel to each other, the guide roller being convertible as a touch roller so that the position of the guide roller can be alternated with the position of the touch roller.
Thus, according to the touch roller device of the invention, when the web is wound around a winding shaft, the approaching direction of the web to the touch roller and the wrapping direction on the wind roll, with which the touch roller is in pressure contact, are kept in parallel. Consequently, a total tension loaded on the touch roller acts on a fulcrum center of the touch roller and such a position that the winding tension does not affect the contact pressure of the touch roller with the wind roll is maintained. In addition, the approaching angle of the web to the touch roller in pressure contact with the wind roll is adjusted by altering the position of the guide roller whereby air is prevented from being entrained between the touch roller surface and the web embracing the touch roller and no small wrinkles are formed in the wound web, thus avoiding a degradation in quality of the web.